This invention relates to a method and apparatus for controlling the cleaning of turbine blades of a turbocharger used with an engine. Specifically the invention concerns sensing an operating parameter of the turbocharger and in response to a degradation in performance as determined by sensing that parameter initiating a cleaning operation to remove accumulated deposits.
Turbochargers are used in conjunction with an engine for numerous reasons. A turbocharger driven by engine exhaust gases uses energy from the exhaust gas that would otherwise be wasted. The turbocharger acts to increase the engine power output by providing higher charge-air density such that more fuel can be burned in each engine cycle, scavenges airflow to clear the cylinders of combustion products and acts to further cool engine parts allowing for power increases. The utilization of a turbocharger with an engine results in increased horsepower output, higher brake mean effective pressure because the higher air density improves engine performance at low loads and permits the engine to operate not only at an optimum efficiency point but also at reduced speeds and loads. The use of a turbocharger may further act to restore sea level ratings on engines operating at high altitudes by compensating for reduced atmospheric pressures, and may make possible maximum speed acceleration to synchronous speed for fast reliable starts as well as reducing fuel and oil consumption.
The exhaust gas from the engine is used as the driving fluid for powering the turbine portion of the turbocharger. The turbine portion is connected by a shaft to the compressor portion of the turbocharger which acts to compress intake air to be delivered to the engine. The exhaust gas powering the turbocharger contains contaminants and particulates caused by incomplete combustion and fuel contaminants. The amount of contaminants released from the engine in the exhaust is a function of the fuel used. Should a "dirty" fuel such as a heavy diesel fuel be utilized, then significant particulates may be discharged with the exhaust.
The utilization of heavy diesel fuels causes buildup of contaminants on the turbine blades causing loss of blade flow path area and adversely affecting performance of the turbocharger. It is necessary to strategically place and suitably size water wash nozzles to periodically clean the blades to restore the blades to a clean condition and thereby to restore full performance to the turbocharger all while the turbocharger remains in service. It is additionally advantageous to provide a control system for automatically or semi-automatically performing this function.